Abstract: A semiconductor wafer and magnetic disk edge detection system having a sensor unit comprising a dual beam light source spatially oriented so that the beams focus and converge at a single point external to the sensor unit, and dual light detectors spatially oriented to allow detection of light reflected from the edges of the wafers and disks even where the angle of incidence of the light onto the edge deviates significantly from the perpendicular. The sensor unit works in operative combination with a scanning motion means to move the sensor across the edges of the wafers or disks to be detected, typically by attachment of the sensor unit to a linear motor or a robotic arm, or alternately, by manually detecting the edges of the wafers and disks.

Abstract: Emulsifier compositions comprising a mixture of quebracho, a surfactant, water, and a pH adjusting reagent for dry and aqueous anionic emulsifiers for producing universal bitumen-in-water emulsions. These emulsifiers are particularly useful in producing stable, anionic asphalt-in-water emulsions that are universal, i.e., they can be used as is or with a wide variety of fillers, additives, pigments and the like, including fine particulate materials, without premature breaking. In the preferred emulsifier, crude, spray-dried quebracho is mixed with an alpha olefin sulfonate containing 10 to 20 carbon atoms, and the pH is preferably adjusted to pH 10 producing an anionic emulsifying agent. The pH may be adjusted from pH 4.5 to pH 11.5. Asphaltic emulsions made with the quebracho emulsifier exhibit enhanced stability, increased viscosity, high ionic headroom and decreased drying times.